The recombinational environment influences patterns of molecular evolution through the effects of Hill–Robertson interference. Here, we examine genome-wide patterns of gene expression with respect to recombinational environment in Drosophila melanogaster. We find that regions of the genome lacking crossing over exhibit elevated levels of expression, and this is most pronounced for genes on the entirely non-crossing over fourth chromosome. We find no evidence for differences in the patterns of gene expression between regions of high, intermediate and low crossover frequencies. These results suggest that, in the absence of crossing over, selection to maintain control of expression may be compromised, perhaps due to the accumulation of deleterious mutations in regulatory regions. Alternatively, higher gene expression may be evolving to compensate for defective protein products or reduced translational efficiency.
We are very grateful to Daniel Halligan for assistance with the statistical analysis package R, Beatriz Vicoso for assistance with the EST database, Andrea Betancourt for drawing our attention to POF and two anonymous reviewers for useful comments on the manuscript. P.R.H. was supported by a grant from NERC to B.C., F.M.W. by a Marie Curie Early Stage Fellowship and B.C. by the Royal Society.
- gene expression
- crossing over